Unless otherwise indicated herein, the materials described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
All-pass filters are widely used in the analog signal processing as group-delay equalizers in video, communication, and instrumentation applications. First-order all-pass filters can also be used as a building block to realize different types of second-order filters and quadrature oscillators. Some popular approaches in the continuous-time integrated filter design involve at least an operational transconductance amplifier and capacitor (OTA-C) due to its certain desired bandwidth and dynamic range.